Antimony and germanium complexes useful for cvd/ald of metal thin films

ABSTRACT

Antimony, germanium and tellurium precursors useful for CVD/ALD of corresponding metal-containing thin films are described, along with compositions including such precursors, methods of making such precursors, and films and microelectronic device products manufactured using such precursors, as well as corresponding manufacturing methods. The precursors of the invention are useful for forming germanium-antimony-tellurium (GST) films and microelectronic device products, such as phase change memory devices, including such films.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation under 35 USC 120 of U.S. patent application Ser.No. 13/168,979 filed Jun. 26, 2011, and issued as U.S. Pat. No.8,268,665 on Sep. 18, 2012, which in turn is a continuation under 35 USC120 of U.S. patent application Ser. No. 12/860,906 filed Aug. 22, 2010,and issued as U.S. Pat. No. 8,008,117 on Aug. 30, 2011, which in turn isa continuation under 35 USC 120 of U.S. patent application Ser. No.12/307,101 filed Feb. 20, 2009, and issued as U.S. Pat. No. 7,838,329 onNov. 23, 2010, which in turn is a U.S. national phase under theprovisions of 35 USC §371 of International Application No.PCT/US2007/063830 filed Mar. 12, 2007, which in turn claims the benefitunder 35 USC §119 of U.S. Provisional Patent Application No. 60/864,073filed Nov. 2, 2006, and the benefit under 35 USC §119 of U.S.Provisional Patent Application No. 60/887,249 filed Jan. 30, 2007. Thedisclosures of all such applications and patents are hereby incorporatedherein by reference in their respective entireties, for all purposes.

FIELD OF THE INVENTION

The present invention relates to antimony and germanium complexes usefulfor CVD/ALD of metal thin films, to compositions including suchcomplexes and to processes for depositing metal films on substratesusing such complexes and compositions.

DESCRIPTION OF THE RELATED ART

Antimonides have been utilized in infrared detectors, high-speed digitalcircuits, quantum well structures and recently as a critical componenttogether with germanium (Ge) and tellurium (Te) in phase changechalcogenide nonvolatile memory technology utilizinggermanium-antimony-tellerium (Ge₂Sb₂Te₅) films.

Phase-change random access memory (PRAM) devices based on Ge—Sb—Te (GST)thin films utilize a reversible transition from a crystalline state toan amorphous state associated with changes in resistivity of the filmmaterial. The film material itself for high-speed commercialmanufacturing and performance reasons is desirably formed usingtechniques such as chemical vapor deposition (CVD) and atomic layerdeposition (ALD).

Despite their promise, there are substantial challenges facing theefforts being made to grow reproducible, high-quality antimonide, Sb₂Te₃and GST films by CVD and atomic layer deposition ALD at low temperature.These challenges include the following:

(1) a very limited number of antimony CVD/ALD precursors is currentlyavailable, most being alkyl-based compounds such as Me₃Sb, Et₃Sb,(iPr)₃Sb and Ph₃Sb or hydride-based compounds such as SbH₃, and theseprecursors suffer from various deficiencies including low thermalstability, low volatility, synthetic difficulties and high deliverytemperatures;

(2) the compatibility of such currently available antimony precursorswith germanium or tellurium precursors is undetermined as far as theirability to reproducibly grow microelectronic device quality GST films,and the growth of antimonide films has associated process difficulties,including sensitivity to the V/III ratio and decomposition temperature;and

(3) the deposited metal films formed from such precursors aresusceptible to carbon or heteroatom contamination deriving from theprecursor that can result in low growth rates, poor morphology andcompositional variations in the films.

Similar issues are encountered in the availability and selection ofsuitable germanium precursors for deposition of GST films, and in theuse of germanium precursors for forming epitaxially grown strainedsilicon films, e.g., SiGe films.

Germane (GeH4) is conventionally used to form germanium films butrequires deposition temperatures above 500° C. as well as rigoroussafety controls and equipment. Other available Ge precursors requiretemperatures above 350° C. for deposition of Ge films, or otherwiseexhibit insufficient vapor pressures for transport or produce low filmgrowth rates. Ideally, the germanium precursor can be used in CVD/ALDprocesses at low temperatures, on the order of 300° C. and below, toform GST alloy thin films at high deposition rates, and with low carbonimpurity levels in the resulting films.

In consequence, the art continues to seek new antimony and germaniumprecursors for use in deposition of corresponding metal and metal alloyfilms by CVD and ALD techniques.

SUMMARY OF THE INVENTION

The present invention relates to antimony and germanium precursorsuseful for CVD/ALD of corresponding metal-containing thin films, tocompositions including such precursors, methods of making suchprecursors, and films and microelectronic device products manufacturedusing such precursors, as well as corresponding manufacturing methods.

In one aspect, the invention relates to a metal complex selected fromamong complexes of formulae (A), (B), (C), (D) and (E)(I)-(E)(XVI):

Sb(NR¹R²)(R³N(CR⁵R⁶)_(m)NR⁴)  (A)

wherein:R¹, R², R³, and R⁴ may be the same as or different from one another, andare independently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₂-C₆alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, C₆-C₁₀ aryl,each of R⁵ and R⁶ may be the same as or different from one another andare independently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀aryl; andm is an integer from 1 to 4 inclusive;

Sb(R¹)(R²N(CR⁴R⁵)_(m)NR³)  (B)

wherein:R¹, R², and R³ may be the same as or different from one another, and areindependently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₂-C₆ alkenyl(e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀ aryl;each of R⁴ and R⁵ may be the same as or different from one another andis independently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀aryl; andm is an integer from 1 to 4 inclusive;

Sb(R¹)_(3-n)(NR²R³)_(n)  (C)

wherein:R¹, R² and R³ may be the same as or different from one another and areindependently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), silyl, C₃-C₆ alkylsilyl,C₆-C₁₀ aryl and —NR⁴R⁵, wherein each of R⁴ and R⁵ is selected from amongH and C₁-C₄; andn is an integer from 0 to 3 inclusive;

(R⁴)_(n)Sb(E(R¹R²R³))_(3-n)  (D)

wherein:R¹, R², R³, and R⁴ may be the same as or different from one another, andare independently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₃-C₆alylsilyl, C₆-C₁₀ aryl, and alkylamino of the formula —NR⁵R⁶ whereineach of R⁵ and R⁶ is independently selected from H and C₁-C₄ alkyl;E is silicon (Si) or germanium (Ge); andn is an integer from 0 to 3 inclusive;(E) germanium precursors of the following formulae I-XVI:

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl;

wherein:R and R′ may be the same as or different from one another, and each Rand R′ is independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl,C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;wherein:

R, R′, R₁ and R₂ may be the same as or different from one another, andeach is independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl,C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;wherein:R, R₁ and R₂ may be the same as or different from one another, and eachis independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl; andn is an integer from 0 to 4 inclusive;

wherein:R¹, R², R³, R⁴, R⁵ and R⁶ may be the same as or different from oneanother, and each is independently selected from H, C₁-C₆ alkyl, C₂-C₅alkenyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;

wherein:R is selected from H, C₁-C₆ alkyl, and C₆-C₁₀ aryl; andx is 0, 1 or 2;wherein:

R₁, R₂, R₃ and R₄ may be the same as or different from the others, andeach is independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl;

wherein:R₁, R₂, R₃, R₄, and R₅ may be the same as or different from one another,and each is independently selected from among H, C₁-C₆ alkyl, silyl,—Si(R′)₃, C₆-C₁₀ cycloalkyl, C₆-C₁₀ aryl, —(CH₂)_(x)NR′R″, and—(CH₂)_(x)OR′″, wherein x=1, 2 or 3, and R′, R″ and R′″ may be the sameas or different from one another, and each is independently selectedfrom C₁-C₆ alkyl;

wherein:R′ and R″ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl; andeach X is independently selected from among C₁-C₆ alkyl, C₁-C₆ alkoxy,—NR¹R², and —C(R³)₃, wherein each of R¹, R² and R³ is independentlyselected from H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and—Si(R⁴)₃ wherein each R⁴ is independently selected from C₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

R₁TeR₂  XIII

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

R₁Te(NR₂R₃)  XIV

wherein:R₁, R₂ and R₃ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independently selected fromC₁-C₆ alkyl;

R₁Te—TeR₂  xv

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl; and

R₁R₂R₃R₄Ge  xvI

wherein:R₁, R₂, R₃, and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl.

In another aspect, the invention relates to a vapor of anabove-described metal complex.

In another aspect, the invention relates to a precursor mixtureincluding germanium precursor, antimony precursor and telluriumprecursor, wherein at least one of the germanium precursor and antimonyprecursor includes a precursor selected from among the metal complexesof formulae (A), (B), (C), (D) and (E)(I)-(XVI) above.

In a further aspect, the invention relates to precursor compositioncomprising a metal complex of the invention, in a solvent medium.

A further aspect of the invention relates to method of depositing metalon a substrate, comprising contacting the substrate with precursor vaporcomprising vapor of a metal complex of the invention.

Additional aspects of the invention relate to methods of making theprecursors of the invention.

A further aspect of the invention relates to Sb(NMeEt)₃, Sb(CH═CMe₂)₃and Sb(CH₂CH═CH₂)₃.

In another aspect, the invention relates to a packaged precursor supplysystem comprising a package containing a metal complex of the invention.

Yet another aspect of the invention relates to a germanium complex whosestructure and properties are more fully discussed hereinafter.

In another aspect, the invention relates to a method of depositinggermanium on a substrate, comprising contacting the substrate withprecursor vapor comprising vapor of a germanium (II) complex selectedfrom among the following:

Another aspect of the invention relates to a method of method ofdepositing germanium on a substrate, comprising contacting the substratewith precursor vapor comprising vapor ofdialkylaminotriisopropylgermane.

The invention also contemplates a precursor vapor comprising vapor ofdialkylaminotriisopropylgermane, in another aspect of the invention.

One aspect of the invention relates to a method of depositing germaniumon a substrate, comprising contacting the substrate with a precursorvapor comprising vapor of a germanium complex including ligands selectedfrom among allyl, benzyl, t-butyl, cylopentadienyl, hydride, phenyl,alkyl, bidentate amines and N,N-dialkylethylenediamine.

Another aspect of the invention relates to forming a GST film on asubstrate, comprising contacting the substrate with a precursor vaporcomprising vapor of a germanium complex of the invention, vapor of anantimony complex, and vapor of a tellurium complex.

Another aspect of the invention relates to adialkylaminotriisopropylgermane complex, e.g.,diethylaminotriisopropylgermane and ethylmethylaminotriisopropylgermane.

A still further aspect of the invention relates to a method of forming agermanium-containing film on a substrate, comprising contacting thesubstrate with a precursor vapor comprising vapor ofdiethylaminotriisopropylgermane or ethylmethylaminotriisopropylgermane.

A still further aspect of the invention relates to a method of making amicroelectronic device, comprising chemical vapor deposition or atomiclayer deposition of a metal-containing film on a substrate from aprecursor vapor comprising vapor of at least one precursor as describedherein.

Where a range of carbon numbers is provided herein, in description of acorresponding chemical moiety, it is understood that each interveningcarbon number and any other stated or intervening carbon number value inthat stated range, is encompassed within the invention, e.g., C₁-C₆alkyl is understood as including methyl (C₁), ethyl (C₂), propyl (C₃),butyl (C₄), pentyl (C₅) and hexyl (C₆), and the chemical moiety may beof any conformation, e.g., straight-chain or branched, it being furtherunderstood that sub-ranges of carbon number within specified carbonnumber ranges may independently be included in smaller carbon numberranges, within the scope of the invention, and that ranges of carbonnumbers specifically excluding a carbon number or numbers are includedin the invention, and sub-ranges excluding either or both of carbonnumber limits of specified ranges are also included in the invention.

As used herein, the term “film” refers to a layer of deposited materialhaving a thickness below 1000 micrometers, e.g., from such value down toatomic monolayer thickness values. In various embodiments, filmthicknesses of deposited material layers in the practice of theinvention may for example be below 100, 10, or 1 micrometers, or invarious thin film regimes below 200, 100, or 50 nanometers, depending onthe specific application involved.

It is noted that as used herein and in the appended claims, the singularforms “a”, “and”, and “the” include plural referents unless the contextclearly dictates otherwise.

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the nuclear magnetic resonance spectrum of Sb(NMeEt)₃.

FIG. 2 shows the nuclear magnetic resonance spectrum of Sb(NMe₂)₃.

FIG. 3 is a simultaneous thermal analysis (STA) graph for Sb(NMeEt)₃ andSb(NMe₂)₃, in which percentage thermogravimetry (TG) is plotted as afunction of temperature, in degrees Centigrade.

FIG. 4( a) is a gas chromatography (GC) spectrum for suchethylmethylaminotriisopropylgermane product, and FIG. 4( b) is acorresponding tabulation of peak data for such GC spectrum. FIG. 4( c)is a mass spectrum for the ethylmethylaminotriisopropylgermane product.FIG. 4( d) shows the nuclear magnetic resonance spectrum of iPr₃GeNEtMe.

FIG. 5 is an STA spectrum of the ethylmethylaminotriisopropylgermaneproduct, showing differential scanning calorimetry (DSC) data andthermogravimetric (TG) data, as a function of temperature.

FIG. 6 is an Arrhenius plot of deposition rate, in A/min, as a functionof inverse Kelvin temperature, showing the improvement in Ge depositionwith ammonia co-reactant.

FIG. 7 is a plot of deposition rate, in A/min, as a function of volumepercent ammonia introduced in the deposition operation.

FIG. 8 is a schematic representation of a schematic of a GST devicestructure.

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS THEREOF

The present invention relates to antimony and germanium precursorsuseful for CVD/ALD of corresponding metal-containing thin films, tocompositions including such precursors, methods of making suchprecursors, and films and microelectronic device products manufacturedusing such precursors, as well as corresponding manufacturing methods.

The invention relates in one aspect to new classes of antimonyprecursors, of the following formulae (A), (B) and (C):

Sb(NR¹R²)(R³N(CR⁵R⁶)_(m)NR⁴)  (A)

wherein:R¹, R², R³, and R⁴ may be the same as or different from one another, andare independently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₂-C₆alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, C₆-C₁₀ aryl,each of R⁵ and R⁶ may be the same as or different from one another andare independently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀aryl; andm is an integer from 1 to 4 inclusive;

Sb(R¹)(R²N(CR⁴R⁵)_(m)NR³)  (B)

wherein:R¹, R², and R³ may be the same as or different from one another, and areindependently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₂-C₆ alkenyl(e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀ aryl;each of R⁴ and R⁵ may be the same as or different from one another andis independently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), C₃-C₆ alkylsilyl, and C₆-C₁₀aryl; andm is an integer from 1 to 4 inclusive;

Sb(R¹)_(3-n)(NR²R³)_(n)  (C)

wherein:R¹, R² and R³ may be the same as or different from one another and areindependently selected from hydrogen, C₁-C₆ alkyl, C₃-C₆ cycloalkyl,C₂-C₆ alkenyl (e.g., vinyl, allyl, etc.), silyl, C₃-C₆ alkylsilyl,C₆-C₁₀ aryl and —NR⁴R⁵, wherein each of R⁴ and R⁵ is selected from amongH and C₁-C₄; andn is an integer from 0 to 3 inclusive.

The invention in another aspect relates to germanyl and silyl antimonyprecursors of formula (D):

(R⁴)_(n)Sb(E(R¹R²R³))_(3-n)  (D)

wherein:R¹, R², R³, and R⁴ may be the same as or different from one another, andare independently selected from C₁-C₆ alkyl, C₃-C₆ cycloalkyl, C₃-C₆alylsilyl, C₆-C₁₀ aryl, and alkylamino of the formula —NR⁵R⁶ whereineach of R⁵ and R⁶ is independently selected from H and C₁-C₄ alkyl;E is silicon (Si) or germanium (Ge); andn is an integer from 0 to 3 inclusive.

The foregoing precursors may be usefully employed for CVD and ALD of Sb,Sb/Ge, Sb/Te and GST films.

Such precursors may also be used in low temperature depositionapplications with reducing co-reactants such as hydrogen, hydrogenplasma, amines, imines, hydrazines, silanes, silyl chalcogenides (e.g.,(Me₃Si)₂Te), germanes (e.g., GeH₄), ammonia, alkanes, alkenes andalkynes.

When specific precursors are in a liquid state, they may be used forliquid delivery in neat liquid form.

Alternatively, when such precursors are in a liquid or solid state, theymay be employed in suitable solvents, as a solution or suspension of theprecursor. In specific applications, suitable solvents for such purposeinclude alkanes (e.g., hexane, heptane, octane and pentane), arylsolvents (e.g., benzene, toluene), amines (e.g., triethylamine,tert-butylamine), imines, hydrazines and ethers.

The choice of a specific solvent composition for a particular antimonyprecursor or for a specific antimony precursor in combination with othergermanium and tellurium precursors, may be readily determined, withinthe skill of the art based on the disclosure herein, to select anappropriate single component or multiple component solvent medium forliquid delivery vaporization and transport of the specific precursorcomponent(s) involved.

In various embodiments, where the antimony precursor is in a solidstate, a solid delivery system may be utilized for delivery of theantimony precursor, such as for example the ProE-Vap® solid delivery andvaporizer system commercially available from ATMI, Inc., Danbury, Conn.,USA.

The antimony precursors of the invention can be “fine-tuned” by choiceof appropriate substituents, within the broad formulae set outhereinabove, to provide desired characteristics of thermal stability,volatility and compatibility with other co-reagents or components in amulti-component precursor system.

The antimony precursors of the invention are readily synthesized, bysynthetic routes including those described below.

The antimony precursor of the general formula (A):

can for example be synthesized according to the following reactionscheme (A):

and the antimony precursor of the general formula (B):

can be synthesized according to the following reaction scheme (B):

or by the following reaction scheme (C):

The antimony precursor of the general formula (C) can be formed bysynthesis in a corresponding manner.

The antimony precursor of the general formula (D), having the followingstructure:

can for example be synthesized according to the following reactionschemes (D), when n is zero, or (E), when n is 2:

wherein X is halo (fluorine, bromine, chlorine, iodine).

In the foregoing synthetic examples, RMgX and RLi can be used asalternative synthesis reagents.

As specific examples illustrative of precursors of the invention, theprecursors Sb(NMeEt)₃, Sb(CH═CMe₂)₃, Sb(CH₂CH═CH₂)₃ and Sb(NMe₂)₃ weresynthesized and characterized. The precursors Sb(NMe₂)₃ and Sb(NMeEt)₃were determined to exhibit photo-sensitivity and therefore to requirestorage in a container protected from light exposure or in otherphoto-resistant packaging, to avoid light-induced decomposition thereof.Similar considerations are applicable to Sb(CH═CMe₂)₃ andSb(CH₂CH═CH₂)₃.

FIG. 1 shows the nuclear magnetic resonance spectrum of Sb(NMeEt)₃ andFIG. 2 shows the nuclear magnetic resonance spectrum of Sb(NMe₂)₃.

FIG. 3 is a simultaneous thermal analysis (STA) graph for these twoprecursors, Sb(NMeEt)₃ and Sb(NMe₂)₃, in which percentagethermogravimetry (TG) is plotted as a function of temperature, indegrees Centigrade.

The invention in another aspect relates to germanium precursors usefulfor CVD and ALD deposition of germanium films on substrates, of thefollowing formulae I-XVI:

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl;

wherein:R and R′ may be the same as or different from one another, and each Rand R′ is independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl,C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;

wherein:

R, R′, R₁ and R₂ may be the same as or different from one another, andeach is independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl,C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;

(R)_(4-n)Ge(NR₁R₂)_(n)  IV

wherein:R, R₁ and R₂ may be the same as or different from one another, and eachis independently selected from H, C₁-C₆ alkyl, C₂-C₅ alkenyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl; andn is an integer from 0 to 4 inclusive;

wherein:R¹, R², R³, R⁴, R⁵ and R⁶ may be the same as or different from oneanother, and each is independently selected from H, C₁-C₆ alkyl, C₂-C₅alkenyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ isindependently selected from C₁-C₆ alkyl;

wherein:R is selected from H, C₁-C₆ alkyl, and C₆-C₁₀ aryl; andx is 0, 1 or 2;

wherein:R₁, R₂, R₃ and R₄ may be the same as or different from the others, andeach is independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl;

wherein:R₁, R₂, R₃, R₄, and R₅ may be the same as or different from one another,and each is independently selected from among H, C₁-C₆ alkyl, silyl,—Si(R′)₃, C₆-C₁₀ cycloalkyl, C₆-C₁₀ aryl, —(CH₂)_(x)NR′R″, and—(CH₂)_(x)OR′″, wherein x=1, 2 or 3, and R′, R″ and R′″ may be the sameas or different from one another, and each is independently selectedfrom C₁-C₆ alkyl;

wherein:R′ and R″ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl; andeach X is independently selected from among C₁-C₆ alkyl, C₁-C₆ alkoxy,—NR¹R², and —C(R³)₃, wherein each of R¹, R² and R³ is independentlyselected from H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and—Si(R⁴)₃ wherein each R⁴ is independently selected from C₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

wherein:R₁, R₂, R₃ and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

R₁TeR₂  XIII

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl;

R₁Te(NR₂R₃)  XIV

wherein:R₁, R₂ and R₃ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independently selected fromC₁-C₆ alkyl;

R₁Te—TeR₂  XV

wherein:R₁ and R₂ may be the same as or different from one another, and areindependently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl; and

R₁R₂R₃R₄Ge  XVI

wherein:R₁, R₂, R₃, and R₄ may be the same as or different from one another, andare independently selected from among H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl,C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ is independently selected fromC₁-C₆ alkyl.

The synthesis of the above-described germanium precursors can variouslybe carried out in a ready manner, utilizing synthetic preparations ofthe types variously shown below. In each instance RMgCl, RMgBr, RMgI,RLi, and RNa can be used as alternative reagents. Further, GeBr₄ can beused in place of GeCl₄; LiNR₂ can be replaced by NaNR₂ or KNR₂; andNa(C₅R₅) can be used as an alternative to K(C₅R₅). Moreover, amulti-step synthetic approach may be employed to generate mixed alkylspecies through oxidative addition to a Ge(II) complex to generateGe(IV) precursors, as shown below:

wherein:R, R′, and R″ may be the same as or different from one another, and eachis independently selected from H, C₁-C₆ alkyl, C₂-C₆ alkenyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R₃)₃ wherein each R₃ is independentlyselected from C₁-C₆ alkyl, and M is Li, Na, MgCl, MgBr, or MgI.

Germanium (IV) Precursors for GST Films

and correspondingly a tetraallylgermanium complex

can be formed from such tetrachlorogermanium starting material using acorresponding allyl Grignard reagent R*MgCl, wherein R* is allyl

Ge Precursors for GST Films

Illustrative Ge(II) compounds that may be usefully employed for CVD orALD of germanium-containing films include the following:

In various embodiments of the invention, dialkylaminoisopropylgermaneprecursors are used for CVD/ALD formation of GST thin films. Suchprecursors may be synthesized by a reaction scheme such as that shownbelow:

to form germanium complexes such as:

The above-described germanium precursors are useful for CVD and ALDapplications, to deposit germanium-containing films on substrates.Tetrakisamidogermanes and triisopropylamines useful for suchapplications and amenable to transport with a heated bubbler include,for example, Ge(NMe₂)₄, Ge(NEtMe)₄, Ge(NEt₂)₄, iPr₃GeCl, iPr₃GeNMe₂,iPr₃GeNEtMe, and iPr₃GeNEt₂. The volatility of the germanium precursorsof the invention can be readily measured by STA thermogravimetrictechnique (e.g., by determining material transport under atmosphericpressure in argon) and GC analysis.

In specific embodiments of germanium precursors of the present inventioncontaining alkyl substituents, isopropyl substituents are in many casespreferred over methyl groups due to the ability of the isopropylsubstituents to undergo beta-hydrogen elimination, thereby facilitatinglow temperature decomposition processing of the germanium precursor,without producing significant carbon residue.

Nitrogen containing germanium precursors of the invention have theintrinsic benefit in many applications of mediating some incorporationof nitrogen in final films. In this respect, Si- and N-doped GSTmaterials have lower reset currents, thereby enabling a lowertemperature phase-change to occur.

As an additional advantage, various germane precursors of the inventionundergo hydrogermolysis coupling reactions to form Ge—Ge bonds, via thereaction

R₃GeNR₁₂+R₃GeH→R₃Ge—GeR₃,

to yield digermane CVD precursors enabling highly efficientGe-containing film deposition to be achieved, in relation tomono-germane precursors.

The germanium precursors of the invention can contain a wide variety ofligand species as moieties thereof. Such ligands may for exampleinclude, without limitation, allyl, benzyl, t-butyl, cylopentadienyl,hydride, phenyl, and alkyl. Bidentate amines (e.g.N,N-dialkylethylenediamine) can also be used.

The germanium precursors can be delivered in solution or suspension in aliquid delivery technique, using suitable solvent media, or may bedelivered for vapor phase desposition of Ge-containing films by soliddelivery techniques, e.g., as described hereinabove in respect of theantimony precursors of the invention.

In use as CVD/ALD precursors, the Ge precursor may be depositedseparately or in combination with other precursors, e.g., with Sb and Tecomplexes such as iPr₃Sb, Sb(NR₂)₃, iPr₂Te and Te(NR₂)₂ to form GSTfilms.

One illustrative germanium precursor of the invention isGe(triisopropyl)(methylethylamide), referred to sometimes hereinafter asGePNEM. This precursor can be employed to deposit germanium on asubstrate at suitable deposition process conditions, e.g., depositiontemperature in a range of from 300° C. to 450° C., and at pressureranging from subatmospheric to superatmospheric (e.g., in a range offrom about 0.5 torr to 15 atmospheres or more). Set out in Table I belowis a listing of film deposition rate, in Angstroms/minute, at varyingtemperature and pressure conditions, for deposition of germanium onsubstrates from the GePNEM precursor, delivered to the substrate in acarrier gas flow of hydrogen gas at 200 standard cubic centimeters perminute.

TABLE I Film Deposition Rate of Germanium Deposited at VaryingTemperature and Pressure Conditions Temperature Temperature PressurePressure (° C.) 1/T (K) 0.8 torr 8 torr 300 0.001745201 0.14 Å/min 0.35Å/min 320 0.001686341 0.45 Å/min 340 0.001631321 1.32 Å/min 0.8 Å/min360 0.001579779 1.48 Å/min 1.28 Å/min 380 0.001531394 2.4 Å/min 2.7Å/min 400 0.001485884 3.4 Å/min 2.3 Å/min 420 0.001443001 6.8 Å/min 10.5Å/min 440 0.001403   6.5 Å/min GePNEM deposition with 200 SCCM H₂

In another determination of film thicknesses of germanium achieved bydeposition from the GePNEM precursor, deposition carried out for aperiod of 16 minutes gave the following results: (i) temperature=400°C., pressure=800 millitorr, reactant gas H₂, film thickness=57 Å; (ii)temperature=400° C., pressure=800 millitorr, reactant gas NH₃, filmthickness=94 Å; and (iii) temperature=400° C., pressure=8000 millitorr,reactant gas H₂, film thickness=36 Å. These results evidence thesuitability of GePNEM for forming germanium or germanium-containing thinfilms on substrates by vapor deposition techniques.

In various specific embodiments, the invention contemplates a precursormixture including germanium precursor, antimony precursor and telluriumprecursor, wherein at least one of the germanium precursor and antimonyprecursor includes a precursor selected from among the metal complexesof formulae (A), (B), (C), (D) and (E)(I)-(XVI) described hereinabove.

In another aspect, the invention contemplates additional classes ofantimony precursors. Such antimony precursors are suitable for use informing GST films, in conjunction with the use of suitable germanium andtellurium precursors.

Such additional classes of antimony precursors include those of formulae(F), (G), (H), (I), (J), (K), (L) and (M), as defined below:

(F) amimidates, guanidates and isoureates of the formula:

R⁷ _(n)Sb[R¹NC(X)NR²]_(3-n)

wherein:where each R¹ and R² is independently selected from among H, C₁-C₆alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ isindependently selected from C₁-C₆ alkyl;each X is independently selected from among C₁-C₆ alkoxy, —NR⁴R⁵, and—C(R⁶)₃, wherein each of R⁴, R⁵ and R⁶ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R³)₃ wherein eachR³ is independently selected from C₁-C₆ alkyl;each R⁷ is independently selected from among C₁-C₆ alkoxy, —NR⁸R⁹, and—C(R¹⁰)₃, wherein each of R⁸, R⁹ and R¹⁰ is independently selected fromH, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, —Si(R³)₃, and —Ge(R³)₃wherein each R³ is independently selected from C₁-C₆ alkyl; andn is an integer from 0 to 3;(G) tetra-alkyl guanidates of the formula:

R⁵ _(n)Sb[(R¹R²)NC(NR³R⁴)N)]_(3-n)

wherein:each of R¹ and R² is independently selected from among H, C₁-C₆ alkyl,C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁹)₃ wherein each R⁹ isindependently selected from C₁-C₆ alkyl;each of R³ and R⁴ is independently selected from H, C₁-C₆ alkyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁹)₃ wherein each R⁹ is independentlyselected from C₁-C₆ alkyl;each R⁵ is independently selected from among C₁-C₆ alkoxy, —NR⁶R⁷, and—C(R⁸)₃, wherein each of R⁶, R⁷ and R⁸ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, —Si(R⁹)₃, and —Ge(R⁹)₃wherein each R⁹ is independently selected from C₁-C₆ alkyl; andn is an integer from 0 to 3.(H) carbamates and thiocarbamates of the formula:

R⁴ _(n)Sb[(EC(X)E]_(3-n)

wherein:each X is independently selected from among C₁-C₆ alkoxy, —NR¹R², and—C(R³)₃, wherein each of R¹, R² and R³ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁵)₃ wherein eachR⁵ is independently selected from C₁-C₆ alkyl;each R⁴ is independently selected from among C₁-C₆ alkoxy, —NR¹R², and—C(R³)₃, wherein each of R¹, R² and R³ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁵)₃, —Ge(R⁵)₃wherein each R⁵ is independently selected from C₁-C₆ alkyl;E is either O or S; andn is an integer from 0 to 3;(I) beta-diketonates, diketoiminates, and diketiiminates, of theformulae:

[OC(R³)C(X)C(R²)O]_(3-n)Sb(R⁵)_(n)

[OC(R³)C(X)C(R²)N(R¹)]_(3-n)Sb(R⁵)_(n)

[R⁴NC(R³)C(X)C(R²)N(R¹)]_(3-n)Sb(R⁵)_(n)

[(R³)OC(═O)C(X)C(R²)S]_(3-n)Sb(R⁵)_(n)

where each of R¹, R², R³ and R⁴ is independently selected from among H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁶)₃ wherein eachR⁶ is independently selected from C₁-C₆ alkyl;each X is independently selected from among C₁-C₆ alkoxy, —NR⁶R⁷, and—C(R⁸)₃, wherein each of R⁶, R⁷ and R⁸ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁶)₃ wherein eachR⁶ is independently selected from C₁-C₆ alkyl;each R⁵ is independently selected from among guanidinate, amimidate,isoureate, allyl, C₁-C₆ alkoxy, —NR⁹R¹⁰, and —C(R¹¹)₃, wherein each ofR⁹, R¹⁰ and R¹¹ is independently selected from H, C₁-C₆ alkyl, C₅-C₁₀cycloalkyl, C₆-C₁₀ aryl, —Si(R⁶)₃, and —Ge(R⁶)₃ wherein each R⁶ isindependently selected from C₁-C₆ alkyl; andn is an integer from 0 to 3.(J) allyls of the formulae:

R⁴ _(n)Sb[R¹NC(X)C(R²R³)]_(3-n)  (i)

R⁴ _(n)Sb[(R¹O)NC(X)C(R²R³))]_(3-n)  (ii)

R⁴ _(n)Sb[(R¹R⁵)NC(X)C(R²R³))]_(3-n)  (iii)

R⁴Sb[(ONC(X)C(R²R³))]  (iv)

where each R¹, R², R³ and R⁵ is independently selected from among H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁶)₃ wherein eachR⁶ is independently selected from C₁-C₆ alkyl;each X is independently selected from among C₁-C₆ alkoxy, —NR¹R², and—C(R³)₃, wherein each of R¹, R² and R³ is independently selected from H,C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R⁶)₃ wherein eachR⁶ is independently selected from C₁-C₆ alkyl;each R⁴ is independently selected from among guanidinates, amimidates,isoureates, beta-diketonates, diketoiminates, diketiiminates, C₁-C₆alkoxy, —NR⁷R⁸, and —C(R⁹)₃, wherein each of R⁷, R⁸ and R⁹ isindependently selected from H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀aryl, —Si(R⁶)₃, and —Ge(R⁶)₃ wherein each R⁶ is independently selectedfrom C₁-C₆ alkyl; andn is an integer from 0 to 3.(L) cyclopentadienyl (Cp) antimony compounds wherein the Cp moiety is ofthe formulae:

wherein each of R₁, R₂, R₃, R₄ and R₅ can be the same as or differentfrom the others, and each is independently selected from among hydrogen,C₁-C₁₂ alkyl, C₁-C₁₂ alkylamino, C₆-C₁₀ aryl, C₁-C₁₂ alkoxy, C₃-C₆alkylsilyl, C₂-C₁₂ alkenyl, R¹R²NNR³, wherein R¹, R² and R³ may be thesame as or different from one another and each is independently selectedfrom C₁-C₆ alkyl, and pendant ligands including functional group(s)providing further coordination to the antimony central atom, andselected from among aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl,and acetylalkyl, having the following formulae:

wherein: the methylene (—CH₂—) moiety could alternatively be anotherdivalent hydrocarbyl moiety; each of R₁-R₄ is the same as or differentfrom one another, with each being independently selected from amonghydrogen, C₁-C₆ alkyl and C₆-C₁₀ aryl; each of R₅ and R₆ is the same asor different from the other, with each being independently selected fromamong C₁-C₆ alkyl; n and m are each selected independently as having avalue of from 0 to 4, with the proviso that m and n cannot be 0 at thesame time, and x is selected from 1 to 5;

wherein each of R₁-R₄ is the same as or different from one another, witheach being independently selected from among hydrogen, C₁-C₆ alkyl, andC₆-C₁₀ aryl; R₅ is selected from among C₁-C₆ alkyl, and C₆-C₁₀ aryl; andn and m are selected independently as having a value of from 0 to 4,with the proviso that m and n cannot be 0 at the same time;

wherein each of R₁, R₂, R₃, R₄, R₅ is the same as or different from oneanother, with each being independently selected from among hydrogen,C₁-C₆ alkyl, and C₆-C₁₀ aryl; each of R₁′, R₂′ is the same as ordifferent from one another, with each being independently selected fromC₁-C₆ alkyl, and C₆-C₁₀ aryl; and n and m are selected independentlyfrom 0 to 4, with the proviso that m and n cannot be 0 at the same time;

wherein each of R₁-R₄ is the same as or different from one another, witheach being independently selected from among hydrogen, C₁-C₆ alkyl, andC₆-C₁₀ aryl; R₅ is selected from among C₁-C₆ alkyl, C₆-C₁₀ aryl, andC₁-C₅ alkoxy; and n and m are selected independently from 0 to 4, withthe proviso that m and n cannot be 0 at the same time;wherein non-Cp ligand(s) of the antimony Cp compound can optionallyinclude ligands selected from the group consisting of guanidinates,amimidates, isoureates, allyls, beta-diketonates, diketoiminates, anddiketiiminates; and(M) alkyls, alkoxides and silyls with pendent ligands, of the formulae:

R⁵ _(n)Sb[(R¹R²)N(CH₂)_(m)C(R¹R²)]_(3-n)  (i)

R⁵ _(n)Sb[(R¹R²)N(CH₂)_(m)Si(R¹R²)]_(3-n)  (ii)

R⁵ _(n)Sb[(R¹R²)N(CH₂)_(m)O]_(3-n)  (iii)

where each of R¹ and R² is independently selected from among H, C₁-C₆alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀ aryl, and —Si(R³)₃ wherein each R³ isindependently selected from C₁-C₆ alkyl;each R⁵ is independently selected from among guanidinates, amimidates,isoureates, beta-diketonates, diketoiminates, diketiiminates, C₁-C₆alkoxy, —NR⁶R⁷, and —C(R⁸)₃, wherein each of R⁶, R⁷ and R⁸ isindependently selected from H, C₁-C₆ alkyl, C₅-C₁₀ cycloalkyl, C₆-C₁₀aryl, —Si(R³)₃, and —Ge(R³)₃ wherein each R³ is independently selectedfrom C₁-C₆ alkyl;n is an integer from 0 to 3;m is integer from 0 to 4.

Antimony precursors of a general type within the foregoing classes(F)-(M) include precursors having the following structures, wherein thevarious “R” groups in these structures are not necessarily numbered inexact correspondence with the substituent numberings in the aboveformulae, but nonetheless reflect the substituted positions in generalfashion, which will be understood in reference to the above definitionsof the substituents at the various positions of the associatedmolecules.

including the following illustrative complexes:

antimony amides of the formulae

antimony (III) alkyl/amino precursors of the formulae:

and stilbenes with germanium anions, of the formulae:

The antimony precursors of classes (F)-(M) are usefully employed fordeposition of antimony at low temperature with reducing co-reactants,e.g., reactants such as hydrogen, H₂/plasma, amines, imines, hydrazines,silanes, silyl chalcogenides such as (Me₃Si)₂Te, germanes such as GeH₄,ammonia, alkanes, alkenes, and alkynes.

The antimony precursors may be delivered for such deposition via liquiddelivery techniques, in which precursors that are liquids may be used inneat liquid form, and precursors that are solids or liquids may bedelivered in solutions or suspensions, in combination with suitablesolvents, such as alkane solvents (e.g., hexane, heptane, octane, andpentane), aryl solvents (e.g., benzene or toluene), amines (e.g.,triethyl, tert-butylamine), imines and hydrazines. The utility ofspecific solvent compositions for particular antimony precursors can bereadily empirically determined, to select an appropriate singlecomponent or multicomponent solvent medium for liquid deliveryvaporization and transport of the specific antimony precursor that isemployed.

In another aspect of the invention, solid delivery techniques may beemployed, in which the solid precursor is volatilized, to form aprecursor vapor that is delivered to the deposition chamber for formingan antimony or antimony-containing film on the substrate. The solidprecursor may be packaged for such use in a storage and dispensingpackage of suitable character, such as the ProE-Vap solid delivery andvaporizer unit commercially available from ATMI, Inc. (Danbury, Conn.,USA).

The invention also contemplates the use of antimony, germanium andtellurium precursors of the present invention separately for depositionof antimony-containing films, germanium-containing films, andtellurium-containing films, respectively. Thus, an antimony precursor ofthe invention may be employed to deposit an antimony-containing film. Inanother embodiment, a germanium precursor of the invention may beemployed to form a germanium-containing film. In another embodiment, atellurium precursor of the invention may be employed to form atellurium-containing film. In still another embodiment, an antimonyprecursor of the invention and a germanium precursor of the inventionmay be utilized to form an antimony/germanium film. In yet anotherembodiment, an antimony precursor of the invention can be utilized incombination with a tellurium precursor, to form an antimony/telluriumfilm. Another embodiment of the invention involves use of a germaniumprecursor of the invention in combination with a tellurium precursor, toform a germanium/tellurium film.

The antimony and/or germanium precursors of the invention can be used todeposit Ge₂Sb₂Te₅ films on suitable microelectronic device substrates inthe fabrication of phase change memory devices.

Such GST films can be fabricated using continuous CVD or ALD techniquesusing suitable germanium, antimony and tellurium precursors, with atleast one of the germanium and antimony precursors comprising a metalcomplex of the present invention. The precursors may be supplied inappropriate ratios to yield the GST film of desired character. Forexample, ALD may be performed with the precursors (Ge, Sb, Te) beingpulsed in a manner to control composition of the resulting film, e.g.,with a pulse cycle including a sequential introduction of precursorspecies in the sequence Te—Ge—Te—Sb—Te—Ge—Te—Sb—Te, repetitivelyconducted until a desired film thickness has been achieved.

As another variant of deposition techniques that may advantageously beemployed to form films containing antimony and/or germanium, by use ofprecursors of the present invention, other co-reactant species may beadded in the deposition operation, to compositionally modify theresulting film. Examples include use of co-reactants to compositionallymodify the film for oxygen and/or nitrogen incorporation, e.g., withvery small amounts of N₂O, O₂ and NO.

In other embodiments, atomic layer deposition (ALD) and rapid vapordeposition (RVD) techniques may be employed to deposit films containingantimony and/or germanium using precursors of the present invention. Forexample, a rapid surface catalyzed vapor deposition may be employedusing ALD, in which a first precursor vapor is contacted with thesubstrate to form a saturated surface layer of the precursor, followedby exposure to a second precursor vapor, and thereafter by exposure to athird precursor vapor, with inert gas purges being carried out betweenthe respective precursor vapor contacting steps, in which at least oneof the first, second and third precursors comprises an antimony and/orgermanium precursor of the invention and, and in which the precursorcontacting and intervening purge steps are repetitively conducted untila predetermined thickness of deposited film material has been achieved.

More generally, the present invention contemplates a wide variety ofantimony and germanium complexes that can be utilized to formcorresponding Sb- and Ge-containing films. The precursor complexes andcompositions of the invention accordingly can be varied in specificusage, and can comprise, consist, or consist essentially of specificmetal source reagents, or such specific reagents and other precursorspecies. Further, it may be desirable in some applications to employmultiple precursor species of the invention, in combination with oneanother and/or together with other precursor species.

The invention also contemplates specific structural definitions and/orspecifications of precursor complexes in specific embodiments, and theexclusion of specific moieties, ligands and elemental species inspecific embodiments. As an illustrative example, in homoleptictris(dialkylamido)antimony complexes and tetrakis(dialkylamido)germaniumcomplexes of the invention, the alkyl substituents may exclude methyl.As another example, tetrakisdialkylamidogermanes may be excluded incertain embodiments of the invention. As a still further example, ingermanyl and silyl antimony complexes of the invention,trimethylgermanyl and trimethylsilyl species may for example beexcluded. It will therefore be appreciated that the invention admits ofdelimited complexes and compositional features of complexes in variousparticularized embodiments of the invention, for purposes of identifyingprecursor complexes and classes of same that are preferredimplementations of the invention in certain applications thereof.

The synthesis of ethylmethylaminotriisopropylgermane is now described toshow the details of making an illustrative germanium precursor of theinvention.

Example 1 Synthesis of ethylmethylaminotriisopropylgermane

A solution of nBuLi (2M in hexanes, 26.34 mL, 42.14 mmol) was slowlyadded to an ice-cooled solution of ethylmethylamine (3.98 mL, 46.35mmol) in ether (100 mL). The resulting white mixture was stirred for 2hours. Triisopropylchlorogermane (9.16 mL, 42.14 mmol) was addeddropwise and the reaction mixture slowly warmed to room temperature. Themixture was stirred overnight, the solvent evaporated under vacuum, andthe residue washed with pentane (100 mL). The mixture was filteredthrough a medium glass frit under nitrogen and the solvent evaporatedunder vacuum to give 10.7 g, 98% of a colorless liquid. The product waspurified by fractional distillation (40° C., 75 mtorr). ¹H NMR(C₆D₆): δ2.87 (q, 2H, ³J=6.9 Hz, NCH₂CH₃), 2.62 (s, 3H, NCH₃), 1.36 (m,CH(CH₃)₂), 1.18 (d, 18H, ³J=7.2 Hz, CH(CH₃)₂), 1.11 (t, 3H, ³J=6.9 Hz,NCH₂CH₃). ¹³C NMR(C₆D₆): δ 48.42, 38.22 (NCH₂CH₃, NCH₃), 20.19(CH(CH₃)₂), 16.20, 15.79 (NCH₂CH₃, CH(CH₃)₂).

FIG. 4( a) is a gas chromatography (GC) spectrum for suchethylmethylaminotriisopropylgermane product, and FIG. 4( b) is acorresponding tabulation of peak data for such GC spectrum. FIG. 4( c)is a mass spectrum for the ethylmethylaminotriisopropylgermane product.FIG. 4( d) shows the nuclear magnetic resonance spectrum of theethylmethylaminotriisopropylgermane product.

FIG. 5 is an STA spectrum of the ethylmethylaminotriisopropylgermaneproduct, showing differential scanning calorimetry (DSC) data andthermogravimetric (TG) data, as a function of temperature.

Another aspect of the invention relates to tellurium complexes withbeta-diketiminate ligands, which overcome the problems that manytellurium precursors used in deposition applications are veryoxygen-sensitive and light-sensitive, and have an unpleasant odor. Bybase stabilization with beta-diketiminate ligands, a tellurium precursoris obtained of a highly stable character with improved handling andshelf life characteristics, reduced odor, and sufficient volatility fordeposition applications.

The tellurium diketiminate complexes of the invention can be used forCVD/ALD to form Te or Te-containing films. These compounds can be usedin combination with Ge- and/or Sb-compounds to produce Te—Ge—, Te—Sb— orGe—Sb—Te films in varied compositions. A general procedure to synthesizediketiminate ligands has been described in the literature, but suchprocedure is disadvantageous, since very bulky aryl substituents on thecoordinating nitrogen atoms are required.

In contrast, we have discovered that smaller alkyl ligands asiso-propyl, n-butyl, tert-butyl or amine-substituted alkyl groups, asfor example ethylene-dimethylamine, can be advantageously used toproduce superior tellurium diketiminate precursors for CVD/ALDapplications. Smaller substituents on the nitrogen donor atoms providesufficient volatility to form good films at low temperature.

The ligands L can be used as the lithium salt or in a free imine form tosynthesize the desired Te complexes. The lithium salt of the ligand canbe reacted with TeX₄ (wherein X═Cl, Br, I) to generate LTeX₃ by saltelimination, which can then be reacted with either a lithium or aGrignard reagent to produce LTeR₃ (wherein R=alkyl, aryl, amide, silyl).

Alternatively the free imine form of the ligand L can be reacted with atellurium organic compound such as TeMe₄ to produce the desired Tespecies LTeMe₃ by methane elimination. The diketiminate ligands providevery effective base stabilization of the reactive metal centertellurium. The invention therefore provides a new class of Te complexesthat provide greater stability and shelf life, while retainingsufficient volatility to form superior Te films via CVD/ALD at lowtemperatures.

The tellurium complexes of the invention have the formulae (I) and (II):

wherein R₁, R₂ and R₃ they be the same as or different from one another,and each is independently selected from C₁-C₆ alkyl, C₆-C₁₀ aryl, silyland C₁-C₁₂ alkylamine (which includes both monoalkylamine as well asdialkylamine); and

wherein R₁, R₂ and R₃ they be the same as or different from one another,and each is independently selected from C₁-C₆ alkyl, C₆-C₁₀ aryl, silyland C₁-C₁₂ alkylamine (which includes both monoalkylamine as well asdialkylamine).

The beta-diketiminate ligands may for example be synthesized by thefollowing procedure:

The tellurium complexes then can be synthesized by the followingreaction:

or alternatively by the following synthesis reaction:

or by the following synthesis reaction:

The tellurium complexes of the invention are usefully employed asCVD/ALD precursors for deposition of tellurium-containing thin films,e.g., by liquid injection of neat precursor material, or in organicsolvent or by direct evaporation.

The invention in another aspect relates to germanium complexes and theiruse in CVD/ALD for forming germanium-containing films, e.g., GST films,wherein the germanium complexes are selected from among:

wherein the R groups in the second formula may be the same as ordifferent from one another, and each is independently selected fromamong H, C₁-C₆ alkyl, C₆-C₁₀ aryl, C₃-C₈ cycloalkyl, heteroatom groups,and other organo groups.

Another aspect of the invention relates to digermane and strained ringgermanium precursors for CVD/ALD of germanium-containing thin films.Previously employed germanium precursors such as germane that have beenused for forming GST (germanium-antimony-tellurium) films for phasechange memory devices require very high temperature depositionconditions. This in turn makes it difficult to form a pure Ge₂Sb₂Te₅phase material.

The present invention overcomes this deficiency in the provision ofprecursors having a high vapor pressure at ambient conditions, which areuseful to deposit germanium-containing films at temperatures below 300°C.

Germanium-germanium bonds are inherently weak (˜188 kJ/mole) and becomeless stable with electron withdrawing substituents such as chlorine orNMe₂. Such bonds can readily dissociate to form R₃Ge radicals under UVphotolysis or thermolysis, or by chemical oxidation using peroxides,ozone, oxygen or plasma. Commercially available digermanes includehydride, methyl, phenyl, or ethyl groups that require high temperaturesfor decomposition and the resulting films are often contaminated withcarbon residues.

We have overcome such deficiency by the provision of germanium complexesusing as ligands isopropyl, isobutyl, benzyl, allyl, alkylamino,nitriles, or isonitriles to achieve complexes that enabled thedeposition of pure germanium metal films at low temperatures. Inaddition, the invention contemplates strained-ring germanium complexes(e.g., germacyclobutane) that can undergo thermal ring opening togenerate a diradical intermediate that readily dissociates to germylenefragments. The bond dissociation energy of the strained Ge—C bond (63kcal/mol) is considerable lower than Ge—CH₃ (83 kcal/mol), therebyenabling lower temperature film deposition of germanium to be achieved,than has been achievable with the aforementioned conventional germaniumprecursors.

The germanium complexes of the invention include those of formulae(I)-(III) below:

(I) alkyldigermanes of the formula

wherein each R may be the same as or different from the others, and eachis independently selected from among isopropyl, isobutyl, benzyl, allyl,alkylamino, nitriles, and isonitriles;(II) alkyl(dialkylamino)germanes of the formula

_(x)(R₂R₁N)R_(3-x)Ge—GeR′_(3-y)(NR₁R₂)_(y)

wherein each R may be the same as or different from the others, and eachis independently selected from among isopropyl, isobutyl, benzyl, allyl,alkylamino, nitriles, and isonitriles; and(III) strained-ring germane complexes of the formula:

wherein each of R₁, R₂, R₃ and R₄ may be the same as or different fromthe others, and each is independently selected from among H, C₁-C₆alkyl, C₆-C₁₀ aryl, C₃-C₈ cycloalkyl, or a heteroatom group.

The complexes (I) can be synthesized, by way of example, according tothe following synthesis process:

or by the following synthesis:

or by a synthesis such as the following:

or a synthesis procedure such as:

The germanium complexes of formula (II) can be formed by the followingillustrated procedure:

Illustrative synthesis processes that can be employed for forminggermanium complexes of formula (III) includes the following:

The strained ring alkylgermanes are usefully employed as CVD/ALDprecursors for forming germanium-containing thin films on substratesinvolving reactions such as those illustratively shown below.

Strained Ring Alkylgermanes as CVD/ALD Precursors for Thin Metal Films

Another aspect of the invention relates to a single-source precursor forgermanium and tellurium, as useful in the formation of GST films. Suchsingle-source of germanium telluride precursors may be used incombination with an antimony precursor for GST film formation,optionally with co-reactants as may be desirable to provide films ofappropriate stoichiometry for a given application.

The germanium telluride complexes of the invention in one aspect includedialkylgermanetellurones. Suitable dialkylgermanetellurones can besynthesized by oxidative addition reaction of germanium (II) dialkylswith elemental tellurium powder in a solvent medium such astetrahydrofuran (THF). In some instances so it may be desirable toconduct the reaction in the absence of light, depending on thelight-sensitivity of the product germanium-tellurium complex. Anillustrative synthesis procedure is set out below:

The single-source Ge—Te precursors of the invention can beadvantageously used to facilitate lower temperature deposition processesor to increase GST film growth rates in specific applications.

Germanium tellurides of the invention, in another embodiment, can beformed by the following synthesis procedure:

Germanium Telluride ALD/CVD Precursors

Other germanium telluride complexes can be formed by the followingsynthesis process:

or by the following generalized reactions:

R₃GeM+R′_(n)EX→R₃Ge-ER′_(n)

R₃GeX+R′_(n)EM→R₃Ge-ER′_(n)

R₃Ge—X+NaTeR′→R₃Ge—TeR′

wherein E is tellurium; M is Li, Na, or K, X is chlorine, bromine oriodine; and the R and R′ groups may be the same as or different from oneanother, and each is independently selected from among H, C₁-C₆ alkyl,C₆-C₁₀ aryl, C₃-C₈ cycloalkyl, heteroatom groups, and other organogroups.

One Ge—Te complex of the invention is:

wherein each of the R substituents may be the same as or different fromone another, and is independently selected from among H, C₁-C₆ alkyl,C₆-C₁₀ aryl, C₃-C₈ cycloalkyl, heteroatom groups, and other organogroups.

Another aspect of the present invention relates to highly unsymmetricgermanium complexes based on amide ligands, which are useful for lowtemperature (below 300° C.) deposition of a germanium-antimony-tellurium(Ge₂Sb₂Te₅) thin film by a CVD or ALD process. These complexes areselected from among complexes of formulae (I) and (II):

wherein R₁, R₂, R₃, R₄, R₅, R₆ and R₇ may be the same as or differentfrom one another, and each is independently selected from the groupconsisting of C₁-C₆ alkyl, C₆-C₁₀ aryl, silyl, alkylsilyl (e.g.,trimethylsilyl), hydrogen and halogen, or wherein in lieu of —NR₅R₆, thesubstituent coordinated to the germanium central atom is insteadselected from the group consisting of C₁-C₆ alkyl, C₃-C₈ cycloalkyl,C₆-C₁₃ aryl, or halide.

The precursors of formulae (I) and (II) can be delivered to the CVD orALD chamber by liquid delivery techniques, in which the precursor isdissolved or suspended in a suitable solvent medium. Illustrative ofsolvent media that may be employed in the broad practice of the presentinvention are solvents selected from among alkanes (e.g., hexane,heptane, octane and pentane), aromatics (e.g., benzene or toluene), oramines (e.g., triethylamine or tert-butylamine). The precursors can alsobe delivered as neat liquids, or alternatively by solid deliverytechniques, utilizing suitable packaging for volatilization anddispensing. One preferred solid delivery package is the ProE-Vap# soliddelivery and vaporizer unit, commercially available from ATMI, Inc.(Danbury, Conn., USA).

The germanium complexes of formulae (I) and (II) can be synthesizedaccording to the following synthesis schemes, in illustrativeembodiments.

The invention in another aspect relates to tellurium complexes in whichthe tellurium central atom is coordinated to a nitrogen atom, toconstitute a Te—N ligand complex.

Illustrative of such Te—N ligand complexes are the following telluriumcomplexes:

wherein R₁, R₂, R₃, R₄, R₅, R₆ and Z may be the same as or differentfrom one another, and each is independently selected from the groupconsisting of C₁-C₆ alkyl, C₃-C₈ cycloalkyl, C₆-C₁₀ aryl, silyl,alkylsilyl (e.g., trimethylsilyl), hydrogen and halogen, and wherein xis an integer having a value of from 1 to 3.

In another aspect, the invention relates to germanium precursors usefulin phase change memory device fabrication based on chalcogenidematerials that undergo a phase change upon heating and are read out as“0” or “1” based on their electrical resistivity, which changes whetherthe phase change material in the memory cell is in a crystalline oramorphous state. Chalcogenide materials comprise a large number ofbinary, ternary, and quaternary alloys of a number of metals andmetalloids, e.g., GeSbTe, GeSbInTe, and many others.

Phase change memory devices require relatively pure alloys, with wellcontrolled composition. Current processes utilize physical vapordeposition to deposit thin films of these materials. CVD and ALD methodsare desirable for their inherent scalability to large area wafers andfor composition control. A major deficiency in the current art is thehigh deposition temperature needed with current alkyl (e.g., Me₃Sb,Me₂Te) or halide sources, which typically greatly exceed 300° C. and maybe as high as 500° C., which exceeds the allowable thermal budget fordevice integration and can result in the evaporation of the chalcogenidematerial.

The invention in another aspect relates to various materials andprocesses that enable low temperature deposition of chalcogenide alloys.

In one chemical approach, butyl and propyl (especially t-butyl andiso-propyl) substituted alkyl hydrides are employed as precursorcomplexes, e.g., complexes of the formula iPr_(x)MH_(y-x), wherein: x>1;y=oxidation state of the metal (M) center; and y-x may =0.

In another chemical approach, butyl and propyl (especially t-butyl andiso-propyl) substituted alkyl halides are employed as precursorcomplexes, e.g., complexes of the formula iPr_(x)MX_(y-x), wherein: X═F,Cl, Br; x>1; y=oxidation state of the metal (M) center; and y-x may =0.

Such precursors can enhance deposition at lower temperatures via betahydrogen elimination.

In another embodiment, digermanes are employed to lower theincorporation temperature of germanium. Useful compounds in this respectinclude Ge₂H₆, Ge₂Me₆, or Ge₂Et₆. Ge₂ iPr₆ and Ge₂tBu₆, as well as Ge₂(SiMe₃)₆ and Ge₂Ph₆, in which Me=methyl, Et=ethyl, iPr=isopropyl,tBu=t-butyl, and Ph=phenyl.

More generally, compounds of the formula Ge₂R₆ may be employed, whereineach of the R's can be the same as or different from the others, andeach is independently selected from among H, C₁-C₈ alkyl, C₁-C₈fluoroalkyl, C₆-C₁₂ aryl, C₆-C₁₂ fluoroaryl, C₃-C₈ cyclo-alkyl, C₃-C₈cyclo-fluoroalkyl. In addition, Ge₂R₄ compounds including Ge₂Ph₄ can beusefully employed for such purpose, wherein each of the R groups may beas above defined. Additional complexes may be utilized including5-member ring complexes with Ge in the ring. Ge(II) complexes are alsopotentially useful in specific applications, such as cyclopentadienylcompounds of the formula Ge(CpR₅)₂ wherein Cp is cyclopentadienyl andeach of the R's may be the same as or different from one another andeach is independently selected as above. Another germanium compound thatis usefully employed for phase change memory applications isGe(CH(SiMe₃))₂.

In another aspect, the antimony component of GST films can be suppliedfrom a precursor such as triphenylantimony, which is inexpensive andlight-sensitive in character, and has utility in light/UV-activateddeposition processes.

Delivery approaches for precursor delivery to enable low temperaturedeposition of chalcogenide alloys include the use of separate bubblersfor in each precursor for the phase change memory film, liquid injectionof precursor mixtures as an approach to manage disparate volatilitycharacteristics of the several precursors to enable delivery of precisevolumetric flows at desired compositions, and the use of mixtures ofneat liquid or precursor/solvent compositions, as respective techniquesthat may be useful in specific applications.

Film deposition approaches for low temperature deposition ofchalcogenide alloys include: the use of continuous CVD in thermal mode,optionally with reducing gases such as hydrogen; employment of pulsed oratomic layer deposition to separate the dose step from the co-reactantsuch as hydrogen plasma; employment of activation techniques such as UVor other light sources that are “tuned” to the precursor, with a lightbeing continuous with the precursor dosing, or dosed separately to avoidgas-phase reactions; and use of alternative reductive co-reactants suchas germane (GeH₄) advantageously dispensed from sub-atmospheric deliverysystems, such as the SAGE® dispensing package commercially availablefrom ATMI, Inc. (Danbury, Conn., USA), for enhanced safety and reducedcost of ownership for the source gas for the deposition.

The invention further aspect relates to a low-temperature germaniumnitride deposition process using an amimidate-based precursor, as foundto be effective in forming germanium nitride at low temperature. FIG. 6is an Arrhenius plot of deposition log rate, in A/min, as a function of1/T, showing the improvement in Ge deposition with ammonia co-reactantfor germanium methyl amidinate (GeMAMDN).

With hydrogen co-reactant the precursor yields an amorphous Ge film witha deposition rate of about 2A/min at 280° C. When the co-reactant wasswitched to ammonia, the deposition rate increased dramatically. Afactor of 100 in deposition rate was observed at around 240° C., and adeposition rate of 75 A/min was achieved at 200° C. Furthermore, thedeposited thin film turned transparent with ammonia co-reactantindicating the formation of germanium nitride. FIG. 7 shows thedominating effect of ammonia co-reactant on the deposition rate.

The invention in a further aspect relates to N, S, O-heterocyclicgermanium CVD/ALD precursors for deposition of germanium metal films atlow temperature. Illustrative of such precursors are [{MeC(iPrN)₂}₂Ge],[{Me₂N(iPrN)₂}₂Ge], [{nBuC(iPrN)₂}₂Ge], and [{MeC(NCy)₂}₂Ge]. In aspecific embodiment, the precursor [{MeC(iPrN)₂}₂Ge] may be provided ina solution of toluene as a CVD precursor for germanium metal films.

In the formation of GST films, a high deposition rate, on the order of400-500A/min of GST alloy, and 100 A/min for Ge, along with low carbonand heteroatom impurity levels in the film, are required. Highlyvolatile precursors are necessary. Liquid precursors are preferred,however low melting and volatile solids may also be used with a heatedbubbler system (˜50° C.). Heteroatom impurities (Si, O, N) areacceptable below 10%.

The invention in such respect contemplates the use of Ge(II) and Ge(IV)precursors with the following ligands: amidinates, guanidinates,isoureates, diketonates, diketoiminates, diketiminates, carbamates,thiocarbamates, silyls, aminotroponiminate. Mixed ligand precursors arealso included with combinations of the above ligands, or in combinationwith alkyl, dialkylamino, hydrido, or halogen groups.

The germanium precursors can be used alone to deposit metallic germaniumfilms thermally or with a co-reactant, or with iPr₂Te or other suitabletellurium precursors to deposit GeTe layers. Similarly, suitableantimony precursors may be employed to form the ternary GST alloy.Co-reactant gases/liquids usefully employed with such precursors includehydrogen, ammonia, plasma, alkylamines, silanes, and germanes.

The germanium precursors of the invention include:

(1) Ge(IV) amidinates, guanidinates, and isoureates of the formula:

wherein each R group is independently selected from among H, C₁-C₆alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R′)₃ wherein each R′ isindependently selected from C₁-C₆ alkyl; andeach Z is independently selected from among C₁-C₆ alkoxy, —NR₁R₂, H,C₁-C₆ alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R₄)₃ wherein eachR₄ is independently selected from C₁-C₆ alkyl;each Y group is independently selected from among C₁-C₆ alkoxy, —NR₁R₂,and C₁-C₆ alkyl, Si(R₄)₃, and halides (Cl, Br, I), and wherein x isinteger from 0 to 4;(2) Ge beta-diketonates, diketoiminates, diketiminates of the formulae:

wherein each R group is independently selected from among H, C₁-C₆alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R′)₃; each Y group isindependently selected from among C₁-C₆ alkyl, C₆-C₁₃ aryl, C₁-C₆alkoxy, NR₁R₂, Si(R₄)₃, and halides (Cl, Br, I), x is integer from 0 to4, Z atoms are the same or different, selected from O, S, and NR; R isselected from C₁-C₆ alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, Si(R′)₃, R′is C₁-C₆ alkyl, C₆-C₁₃ aryl;(3) Ge carbamates, thiocarbamates of the formulae:

wherein each Z is independently selected from among H, C₁-C₆ alkyl,C₃-C₁₀ cycloalkyl, C₁-C₆ alkoxy, NR₁R₂, C₆-C₁₃ aryl, and —Si(R₄)₃wherein each R₄ is independently selected from C₁-C₆ alkyl or aryl; eachY group is independently selected from among C₁-C₆ alkyl, C₁-C₆ alkoxy,NR₁R₂, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, Si(R₄)₃, and halides (Cl, Br, I),x is integer from 0 to 4, and E is either O or S;(4) Silylgermanes of the formula:

wherein TMS is Si(R″)₃; each R group is independently selected fromamong H, C₁-C₆ alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₂ aryl, and x is integerfrom 0 to 4;(5) Mixed cyclopentadienyl germanes of the formulae:

R_(4-x)GeCp_(x) RGeCp

(RR′N)_(4-x)GeCp_(x) RR′NGeCp

CpGe(amidinate) CpGe(guanidinate)

CpGe(beta-diketiminate)

CpGe(beta-diketonate)

CpGe(isoureate)

wherein each R group is independently selected from among H, C₁-C₆alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R′)₃ wherein each R′ isindependently selected from C₁-C₆ alkyl; andeach Y group is independently selected from among C₁-C₆ alkyl, C₁-C₆alkoxy, NR₁R₂, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, Si(R₄)₃, and halides (Cl,Br, I), x is an integer having a value of from 0 to 4, and Cp ligandsmay also include:

(6) Ge(II) amino-alkoxide of the formula:

wherein each R group is independently selected from among H, C₁-C₆alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R′)₃, wherein each R′ isindependently selected from C₁-C₆ alkyl, and n is an integer having avalue of from 2 to 6;(7) Other N-heterocyclic germylenes of the formulae:

wherein each R group is independently selected from among H, C₁-C₆alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, and —Si(R′)₃, wherein each R′ isindependently selected from C₁-C₆ alkyl; andeach Y group is independently selected from among C₁-C₆ alkoxy, NR₁R₂,H, C₁-C₆ alkyl, C₃-C₁₀ cycloalkyl, C₆-C₁₃ aryl, Si(R₄)₃, or halides (Cl,Br, I);(8) Oxides, dithiolates, thiocarbonates of the formulae:

wherein each R, R′ is independently selected from among C₁-C₆ alkyl,C₃-C₁₀ cycloalkyl, C₁-C₆ alkoxy, NR₁R₂, C₆-C₁₃ aryl, and —Si(R₄)₃wherein each R₄ is independently selected from C₁-C₆ alkyl or aryl, andhalides (Cl, Br, I), and E is either O or S.

The ALD/CVD precursors (1)-(8) described above can be prepared in liquiddelivery formulations using a suitable solvent such as alkanes (e.g.,hexane, heptane, octane, and pentane), aromatics (e.g., benzene ortoluene), or amines (e.g., triethylamine, tert-butylamine). Precursorsmay also be delivered as neat liquids or as solids using a suitablesolid delivery and vaporizer unit (such as the ProE-Vap™ solid deliveryand vaporizer unit commercially available from ATMI, Inc., Danbury,Conn., USA).

Set out below is an identification of various specific germaniumprecursors of the invention.

Ge CVD/ALD Precursors Ge(IV) Precursors

Ge(II) Precursors

The invention in a further aspect contemplates various metal silylamidesuseful for CVD and ALD deposition of thin films.

This aspect of the invention encompasses the synthesis andcharacterization of a class of metal precursors withdisily-azacycloalkyl ligand: R5nM{N[(R₁R₂)Si(CH₂)mSi(R₃R₄)]}ox-n; metalsilylamides particularly with asymmetric elements in the silylamidoligands, R5nM{R4N[Si(R1R2R3)]}ox-n; carbodiimido insertion reaction withthose silylamides to yield the corresponding guanidinate complexes,which can also be used as CVD/ALD precursors.

The “oligomers” of the above-discussed monomers with the same empiricalformula include [R5nM{N[(R1R2)Si(CH2)_(m)Si(R3R4)]}ox-n]_(x) or[R5nM{R4N[Si(R1R2R3)]}ox-n]_(x) where x is an integer having a value of2, 3, etc.

The invention also contemplates precursors with open-structured silazaneligands in which at least one of the Rs has a functional group such asamido, alkoxyl, siloxyl and thienyl: R5nM{(R4R5R6)SiN[Si(R1R2R3)]}ox-n,and its corresponding guanidinates.

The “oligomers” of the above-discussed monomer with the same empiricalformula include [R5nM{(R4R5R6)SiN[Si(R1R2R3)]}ox-n]x where x is aninteger having a value of 2, 3, etc.

Each of R1, R2, R3, R4, R6 and R7 in the about formulae is independentlyselected from among H, C1-C6 alkyl, C3-C10 cycloalkyl, C6-C10 aryl,—Si(R8)3 and —Ge(R8)3 wherein each R8 is independently selected fromC1-C6 alkyl; and —Si(R9)3 wherein each R9 is independently selected fromC1-C6 alkyl; when suitable, pendant ligands attached to theabove-mentioned R1, R2, R3, R4, R6 and R7 include functional group(s)providing further coordination to the metal center, such as, forexample, aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl, andacetylalkyl, wherein suitable groups in these classes include those ofthe following formulae:

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen and C1-C6 alkyl;each of R5 and R6 is the same as or different from the other, with eachbeing independently selected from among C1-C6 alkyl;n and m are each selected independently from 0 to 4 with the provisionthat m and n cannot be 0 at the same time, and x is selected from 1 to5;

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen, C1-C6 alkyl, andC6-C10 aryl; R5 is selected from among C1-C6 alkyl, and C6-C10 aryl; andn and m are selected independently from 0 to 4, with the provision thatm and n cannot be 0 at the same time.

In the metal precursors, each R5 can be independently selected fromamong H, C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, —NR1R2, and—C(R3)3, —Si(R8)3 and —Ge(R8)3 wherein each R3 is independently selectedfrom C1-C6 alkyl; and each of R8 and R8 is independently selected fromH, C1-C6 alkyl, C5-C10 cycloalkyl, C6-C10 aryl, and —Si(R9)3 whereineach R4 is independently selected from C1-C6 alkyl.

In such metal precursors, M can be any of the metals mentioned above(Ta, V, Ti, Nb, Pb, Ni, W, Ca, Ba, In, Y, La, Zr, Hf, Ir, Ru, Pt, Cr,Mo, Ge; Al, Si, Ga, Sc, V, Cr, Fe, Sb, lanthanides, Mn, Co, Ni, Zn, Cd,Te, Hg, Au, Cu, Ag, Sr, Ru) but not limited to them only; OX is theallowed oxidation state of the metal M; n is an integer having a valueof from 0 to ox; and X is halogen.

The above-described precursor materials can be used as low temperaturedeposition precursors with reducing co-reactants such as hydrogen,H2/plasma, amines, imines, hydrazines, silanes, silyl chalcogenides suchas (Me3Si)2Te, germanes such as GeH4, ammonia, alkanes, alkenes,amidines, guanidines, boranes and their derivatives/adducts and alkynes.The precursors may be employed in liquid delivery formulations, and theprecursors that are liquids may be used in neat liquid form, with liquidor solid precursors being employed as desired in suitable solventsincluding alkane solvents (e.g., hexane, heptane, octane, and pentane),aryl solvents (e.g., benzene or toluene), amines (e.g., triethylamine,tert-butylamine), imines, guanidines, amidines and hydrazines.

The utility of specific solvent compositions for particular precursorsmay be readily empirically determined, to select an appropriate singlecomponent or multiple component solvent medium for liquid deliveryvaporization. Solid delivery systems may be employed, of the typepreviously described herein.

The above-described precursors are variously shown below.

The invention in a further aspect relates to tetraalkylguanidinate andketiminate complexes useful as CVD and ALD precursors, including a classof metal precursors with tetraalkylguanidine ligand, e.g., in thecoordination mode (R5) nM{N═C[(NR1R2)(NR3R4)]}ox-n and the semi-labilecoordination mode. Under special circumstances, both coordination modescould theoretically co-exist.

All of such complexes can be synthesized from the corresponding alkalimetal salts with metal halides or alkyls or mixed halides/alkyls/amidesor from the direct reactions between tetraalkylguanidine with metalhalides with the presence of HX absorbents such as NEt3.

The “oligomers” of such monomer with the same empirical formula include[(R5)nM{N═C[(NR1R2)(NR3R4)]}ox-n]x, where x is an integer having thevalue of 2, 3, etc.

Four illustrative Ge (IV) precursors have been synthesized andcharacterized. All of them showed promising thermal behavior andTMG2Ge(NMe2)₂ is a viscous liquid at room temperature.

The invention also contemplates the corresponding guanidinate complexesR5nM{R6NC{N═C[(NR1R2)(NR3R4)]}NR7}ox-n. The “oligomers” of such monomerwith the same empirical formula include[R5nM{R6NC{N═C[(NR1R2)(NR3R4)]}NR7}ox-n]x, where x is an integer havingthe value of 2, 3, etc.

The invention further encompasses a tetraalkylguanidine insertionreaction with metal amides to yield the corresponding guanidinatecomplexes, which can also be used as CVD/ALD precursors, as well asketiminates of the formula (R5)nM{N═C[(R1R2)]}ox-n and its correspondingguanidinate complexes of the formula R5nM{R6NC[N═C(R1R2)]NR7}ox-n. The“oligomers” such monomer with the same empirical formula include[R5nM{R6NC[N═C(R1R2)]NR7}ox-n]x, where x is an integer having the valueof 2, 3, etc.

In the metal complexes described above, each of R1, R2, R3, R4, R6 andR7 is independently selected from among H, C1-C6 alkyl, C3-C10cycloalkyl, C6-C10 aryl, —Si(R8)3 and —Ge(R8)3 wherein each R8 isindependently selected from C1-C6 alkyl; and —Si(R9)3 wherein each R9 isindependently selected from C1-C6 alkyl; when suitable, pendant ligandsattached to the above-mentioned R1, R2, R3, R4, R6 and R7 includingfunctional group(s) providing further coordination to the metal center,such as, for example, aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl,and acetylalkyl, wherein suitable groups in these classes include thoseof the following formula:

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen and C1-C6 alkyl;each of R5 and R6 is the same as or different from the other, with eachbeing independently selected from among C1-C6 alkyl; n and m are eachselected independently from 0 to 4 with the provision that m and ncannot be 0 at the same time, and x is selected from 1 to 5;

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen, C1-C6 alkyl, andC6-C10 aryl; R5 is selected from among C1-C6 alkyl, and C6-C10 aryl; andn and m are selected independently from 0 to 4, with the provision thatm and n cannot be 0 at the same time.

In the metal precursors, each R5 can be independently selected fromamong H, C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, —NR1R2, and—C(R3)3, —Si(R8)3 and —Ge(R8)3 wherein each R3 is independently selectedfrom C1-C6 alkyl; and each of R8 and R8 is independently selected fromH, C1-C6 alkyl, C5-C10 cycloalkyl, C6-C10 aryl, and —Si(R9)3 whereineach R4 is independently selected from C1-C6 alkyl.

In such metal precursors, M can be any of the metals mentioned above(Ta, V, Ti, Nb, Pb, Ni, W, Ca, Ba, In, Y, La, Zr, Hf, Ir, Ru, Pt, Cr,Mo, Ge; Al, Si, Ga, Sc, V, Cr, Fe, Sb, lanthanides, Mn, Co, Ni, Zn, Cd,Te, Hg, Au, Cu, Ag, Sr, Ru) but not limited to them only; OX is theallowed oxidation state of the metal M; n is an integer having a valueof from 0 to ox; and X is halogen.

The above-described precursor materials can be used as low temperaturedeposition precursors with reducing co-reactants such as hydrogen,H2/plasma, amines, imines, hydrazines, silanes, silyl chalcogenides suchas (Me3Si)2Te, germanes such as GeH4, ammonia, alkanes, alkenes,amidines, guanidines, boranes and their derivatives/adducts and alkynes.The precursors may be employed in liquid delivery formulations, and theprecursors that are liquids may be used in neat liquid form, with liquidor solid precursors being employed as desired in suitable solventsincluding alkane solvents (e.g., hexane, heptane, octane, and pentane),aryl solvents (e.g., benzene or toluene), amines (e.g., triethylamine,tert-butylamine), imines, guanidines, amidines and hydrazines.

The utility of specific solvent compositions for particular precursorsmay be readily empirically determined, to select an appropriate singlecomponent or multiple component solvent medium for liquid deliveryvaporization. Solid delivery systems may be employed, of the typepreviously described herein.

The above-described precursors are variously shown below.

Thermal and elemental analysis is set out in the table below, for thefour illustrated precursors previously mentioned as having beencharacterized.

STA Resi- Elemental analysis T₅₀ due C H N Precursor (° C.) (%) (%) (%)(%) Note GeTMG₂Cl₂ 230 3.2 Calc. 32.29 6.51 22.6 NMR Found 31.12 6.2921.69 GeTMG₂Me₂ 182 1.0 Calc. NMR Found GeTMG₂(NMe₂)₂ 219 2.9 Calc. NMR(liquid at R.T.) Found GeTMG₄ 255 1.1 Calc. NMR, Found X-ray

The above-described precursors are variously shown below.

The invention in a further aspect relates to dianionic chelateguanidinate ligands useful for CVD and ALD, and includes a class ofmetal precursors with dianionic chelate guanidine ligands of the formula(R4)nM{(R1)N═C[(NR2)(NR3)]}(ox-n)/2.

All of such precursors can be synthesized from the corresponding alkalimetal salts with metal halides or alkyls or mixed halides/alkyls or fromdirect reactions between guanidines with metal halides with the presenceof HX absorbents such as NEt3. The syntheses of the guanidinate ligandscan be done from the corresponding carbodiimides and primary amines.

The “oligomers” of the above-claimed monomer with the same empiricalformula include [(R4)nM{(R1)N═C[(NR2)(NR3)]}(ox-n)/2]x, where x is aninteger having the value of 2, 3, etc., wherein each R1, R2, R3, R4, isindependently selected from among H, C1-C6 alkyl, C3-C10 cycloalkyl,C6-C10 aryl, —Si(R5)3 and —Ge(R5)3 wherein each R8 is independentlyselected from C1-C6 alkyl; and —Si(R6)3 wherein each R9 is independentlyselected from C1-C6 alkyl; and when suitable, pendant ligands attachedto the above-mentioned R1, R2, R3, R4 including functional group(s)providing further coordination to the metal center, such as, forexample, aminoalkyl, alkoxyalkyl, aryloxyalkyl, imidoalkyl, andacetylalkyl, wherein suitable groups in these classes include those ofthe following formula:

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen and C1-C6 alkyl;each of R5 and R6 is the same as or different from the other, with eachbeing independently selected from among C1-C6 alkyl; n and m are eachselected independently from 0 to 4 with the provision that m and ncannot be 0 at the same time, and x is selected from 1 to 5;

wherein each of R1-R4 is the same as or different from one another, witheach being independently selected from among hydrogen, C1-C6 alkyl, andC6-C10 aryl; R5 is selected from among C1-C6 alkyl, and C6-C10 aryl; andn and m are selected independently from 0 to 4, with the provision thatm and n cannot be 0 at the same time.

In the metal precursors, each R5 can be independently selected fromamong H, C1-C6 alkyl, C3-C6 cycloalkyl, C1-C6 alkoxy, —NR1R2, and—C(R3)3, —Si(R8)3 and —Ge(R8)3 wherein each R3 is independently selectedfrom C1-C6 alkyl; and each of R8 and R8 is independently selected fromH, C1-C6 alkyl, C5-C10 cycloalkyl, C6-C10 aryl, and —Si(R9)3 whereineach R4 is independently selected from C1-C6 alkyl.

In such metal precursors, M can be any of the metals mentioned above(Ta, V, Ti, Nb, Pb, Ni, W, Ca, Ba, In, Y, La, Zr, Hf, Ir, Ru, Pt, Cr,Mo, Ge; Al, Si, Ga, Sc, V, Cr, Fe, Sb, lanthanides, Mn, Co, Ni, Zn, Cd,Te, Hg, Au, Cu, Ag, Sr, Ru) but not limited to them only; OX is theallowed oxidation state of the metal M; n is an integer having a valueof from 0 to ox; and X is halogen.

The above-described precursor materials can be used as low temperaturedeposition precursors with reducing co-reactants such as hydrogen,H2/plasma, amines, imines, hydrazines, silanes, silyl chalcogenides suchas (Me3Si)2Te, germanes such as GeH4, ammonia, alkanes, alkenes,amidines, guanidines, boranes and their derivatives/adducts and alkynes.The precursors may be employed in liquid delivery formulations, and theprecursors that are liquids may be used in neat liquid form, with liquidor solid precursors being employed as desired in suitable solventsincluding alkane solvents (e.g., hexane, heptane, octane, and pentane),aryl solvents (e.g., benzene or toluene), amines (e.g., triethylamine,tert-butylamine), imines, guanidines, amidines and hydrazines.

The utility of specific solvent compositions for particular precursorsmay be readily empirically determined, to select an appropriate singlecomponent or multiple component solvent medium for liquid deliveryvaporization. Solid delivery systems may be employed, of the typepreviously described herein.

The above-described precursors are variously shown below.

A is akali metals, X is halogens and ox is the allowed oxidation stateof M.

An exemplary ligand PriN═C(PriNH)2 was synthesized and characterized asfollows.

Example

To a 250 mL flask charged with 12.6 g PriNCNPri (0.1 mol) and 100 mltoluene, 5.9 g PriNH2 (0.1 mol) was added at 0° C. gradually. Theresulting mixture was then refluxed at 100° C. overnight. After work-up,11.5 g solid PriN═C(PriNH)2 was obtained. (62% yield) Anal. Calcd forC10H23N3: C, 64.81%; H, 12.51%; N, 22.68%. Found: C, 64.73%; H, 12.39%;N, 22.48%.

Selected bond lengths[A]

C(1)-N(3) 1.287(3) C(1)-N(2) 1.358(3) C(1)-N(1) 1.378(3)

The invention in a further aspect relates to a highly selectivegermanium deposition process. Although discussed herein with primaryreference to germanium, this process has applicability to other filmdeposition applications in which the film deposition process isdependent on nucleation processes, e.g., ruthenium deposition.

Phase Change Memory (PCM) is currently considered the leading contenderfor non-volatile memory based on its potential to scale down for severalgenerations. Integrated GST based PCM devices have been made in the formof a large, flat layer with “plug” electrodes. Metalorganic ChemicalVapor Deposition (MOCVD) processes are under development for makingthese films, as it will certainly be necessary to deposit them in 3Dgeometries as device geometries shrink. In future generations, it willbe necessary to scale this operation down to make the entire phasechange chalcogenide section a plug within a via of insulating materialsuch as silicon oxide, silicon nitride or low k dielectric.

An example of this can be seen in FIG. 8, which is a schematic of a GSTdevice structure showing the GST plug, top electrode, bottom electrode,interlayer dielectric and associated layers of the device. Since neitheretching nor CMP of this material is well established, making such a plugis not trivial, since a fairly thick layer is needed in order to allowfor the bulk phase change that stores information in the form of aresistivity change. It would be desirable to grow the material in a“bottom up” way only in the via, without coating the rest of thestructure. In order for this to occur, the deposition process must behighly selective, growing quickly on the desired surfaces and slowly ornot at all on others.

It might also be desirable to have the PCM material have poor contactwith sidewalls of the via so as to reduce thermal contact and crosstalkbetween adjacent cells. Thus it could be desirable to have differentsticking coefficients and nucleation likelihood on different surfaces.

It is also necessary to develop low temperature MOCVD processes formaking these films, at temperatures of 300° C. or less, since somecomponents are volatile enough that stoichiometry control becomesdifficult above this temperature.

During our investigations of Ge precursors for PCMs, an amide-basedprecursor was discovered that has very strong selectivity based onsurface state of the substrate on which it is being grown. Thisprecursor, Ge(NMe2)4, undergoes a deposition rate change of close to1000× over an extremely narrow temperature range, just 10-15° C. This isvirtually unique behavior and we are aware of no other compound thatdoes this.

For such a strong effect to be taking place, it seemed likely that itwas due to changes in the deposition surface and some kind ofautocatalysis. These films were deposited on TiN, which was purchasedcommercially more than a year previously and cleaved into pieces forthese experiments. Ti and TiN rapidly form oxides from exposure toatmosphere, and there is little doubt that the nucleation surface asinserted into the reactor was some form of Ti oxide or oxide nitridemix. Ti changes between various suboxides such as TiO2 and Ti2O3readily, however, so it is possible that under reducing conditions suchas the forming gas which flows through the reactor during heatup on thesubstrate, or even the hydrogen in which deposition takes place, thesurface is altered in a fairly abrupt way at a particular transitiontemperature. Heatup from room temperature was fixed at 4 minutes in allexperiments. This could explain the behavior observed above, withdeposition rate increasing from a few A/min up to 1000 A/min in a 10-15degree C. window, and with the location of this window shiftable by tensof degrees based on the reactant gas and partial pressure of the gasespresent.

In order to test this theory, deposition was carried out on SiO2substrates, and on a piece of TiN which was first heated to 400 C in 8Tof hydrogen before being cooled to deposition temperature over thecourse of 10 minutes. The results included a deposition rate at 280 C ofabout 3 A/min deposited on TiN that had been exposed to air then placedon a susceptor. On a SiO2 substrate, the deposition rate was closer to0.3 A/min, an order of magnitude lower. Meanwhile, on the substratewhich was preheated to 400 C then cooled in a reducing atmosphere in thereactor, deposition rate was close to 600 A/min at 280 C, and the ratewas substantially higher at low temperatures. The preheated substratewas the closest simulation of a standard manufacturing process, where aTiN or similar electrode would be deposited in one part of a clustertool, after which the substrate would be transferred to the CVDdeposition module without any air exposure. The 200:1 ratio betweendeposition rates on preheated TiN and SiO2 is sufficient to obtain avery high selectivity on any combination of surfaces like this one. Itis expected that this ratio would increase still further with clean, “insitu” deposited TiN and SiO2.

The most straightforward potential benefit to the unique behavior ofthis precursor was bottom up fill of the vias to make a plug ofchalcogenide phase change memory material. The Ge initial layer can beused as a somewhat more favorable growth site for a complete suite ofprecursors to help prevent “seams” or voids in the plug.

If it were desirable, it might also be possible to have a plug of PCMmaterial with poor contact to the side walls, providing better thermalisolation and less cross talk between adjacent PCM cells. Slowdeposition and poor nucleation may lead to a poorly adhering layer withpores near the surface.

A more indirect benefit is creation of a semiconductor compatiblenucleation surface for other nucleation sensitive materials. Forexample, it is well known that Ru metal is difficult to grow in a purelyreducing atmosphere; it tends to need some oxygen in its vicinity, formost CVD precursors. In addition, it is very hard to deposit ituniformly on a SiO2 surface. This Ge precursor can be used to form anucleation layer on Si at the bottom of a trench or via so that aslightly oxidizing process can be used, since Ge does not bond asstrongly to oxygen as Si does, or a reducing process which deposits moreeasily on clean metal could be used. This approach can be extended todeposition of materials other than Ru, providing they have some surfacechemistry sensitivity that can be exploited.

In a more sophisticated approach, a surface, metal, nitride and/or Ge,can have its surface chemistry changed via reactant gases (for examplefrom oxide to metal) in order to switch it on and off for purposes ofdeposition from this precursor. This in turn allows a chip surface thatmay have multiple materials exposed to have different surfaces switchedon and off, depending on the layer material and coreactant, relative toGe deposition. The Ge can then be used as a protective layer for furtherchemistry modifications, e.g., as a hard mask, a sacrificial layer, etc.This principle can be extended to other elements than Ge upon findingappropriate precursors with this strong sensitivity to surface anddeposition temperature.

Other chemicals and chemical families that may exhibit this behaviorinclude N-coordinated germanium amides, amidinates, guanidinates, andN-heterocyclic germylenes. The described process is also applicable tometal-organic CVD or ALD precursors comprising a metal selected from Ge,Sb, Te, Be, Mg, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh,Pd, Ag, Cd, Hg, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Sn, Pb, As, P, Bi,Al, Ga, In, Tl, and Si, to which is bound at least one weaklycoordinating ligand selected from among halogen, B-diketiminate,nitrile, isonitrile, aminotroponiminate, carbonyl, phosphido, imido,amine, pyridine, amidinate, guanidinate, nitrosyl, silyl, stibene(R3Sb), sulfide, and cyclopentadienyl.

In a broad aspect, the present invention contemplates metal precursorsof the formula MA_(y)B, wherein M is a metal selected from among Ge, Sband Te, and A is a ligand selected from the group consisting of allligands disclosed herein, and y+x equals the oxidation state on metal M.

While the invention has been has been described herein in reference tospecific aspects, features and illustrative embodiments of theinvention, it will be appreciated that the utility of the invention isnot thus limited, but rather extends to and encompasses numerous othervariations, modifications and alternative embodiments, as will suggestthemselves to those of ordinary skill in the field of the presentinvention, based on the disclosure herein. Correspondingly, theinvention as hereinafter claimed is intended to be broadly construed andinterpreted, as including all such variations, modifications andalternative embodiments, within its spirit and scope.

1. A method of fabricating a phase-change non-volatile memory device structure including a germanium alloy, said method comprising forming a germanium alloy on a substrate, wherein the germanium component of said germanium alloy is deposited on said substrate by vapor deposition of germanium from a germanium amidinate precursor, wherein the germanium amidinate precursor includes Ge(II) or Ge(IV), and at least one amidinate ligand of the formula [RNCXNR]— wherein each R is independently selected from H, C1-C6 alkyl, C3-C10 cycloalkyl, C6-C13 aryl, and —Si(R′)3 wherein each R′ is independently selected from C1-C6 alkyl, and X is selected from among H, C1-C6 alkyl, C1-C6 alkoxy, —NR1R2, and —C(R3)3, wherein each of R1, R2 and R3 is independently selected from H, C1-C6 alkyl, C3-C10 cycloalkyl, C6-C13 aryl, and —Si(R4)3 wherein each R4 is independently selected from C1-C6 alkyl, and wherein non-amidinate ligand(s) are selected from alkyl, alkoxy, dialkylamino, hydrido, —Si(R4)3 and halogen groups.
 2. The method of claim 1, wherein the germanium alloy comprises germanium-antimony-tellurium (GST) alloy.
 3. The method of claim 1, wherein the germanium amidinate precursor comprises germanium bis(n-butyl, N,N-diisopropylamidinate),


4. The method of claim 1, wherein said vapor deposition of germanium is conducted at temperature not exceeding 300° C.
 5. The method of claim 2, wherein the antimony component of said GST alloy is deposited on said substrate by vapor deposition of antimony from an antimony precursor comprising a trialkyl antimony compound or a triamido antimony compound.
 6. The method of claim 5, wherein the antimony precursor comprises a tris-dialkylamido antimony compound.
 7. The method of claim 5, wherein the antimony precursor comprises tris(dimethylamino) antimony.
 8. The method of claim 2, wherein the tellurium component of said GST alloy is deposited on said substrate by vapor deposition of tellurium from a tellurium precursor comprising dialkyl tellurium.
 9. The method of claim 8, wherein the tellurium precursor comprises di-t-butyltellurium.
 10. The method of claim 2, wherein the antimony component of said GST alloy is deposited on said substrate by vapor deposition of antimony from an antimony precursor comprising tris(dimethylamino)antimony, and the tellurium component of said GST alloy is deposited on said substrate by vapor deposition of tellurium from a tellurium precursor comprising di-t-butyltellurium.
 11. The method of claim 10, comprising delivery of said precursors for vapor deposition, in which each of the precursors is delivered separately or in precursor mixture.
 12. The method of claim 11, wherein the tellurium precursor is delivered separately for vapor deposition.
 13. The method of claim 1, wherein the phase-change non-volatile memory device structure includes electrode and dielectric material components.
 14. The method of claim 1, wherein the phase-change non-volatile memory device structure includes an insulating material containing a via within which the GST material is deposited.
 15. The method of claim 14, wherein the insulating material comprises material selected from the group consisting of silicon oxide, silicon nitride, and low k dielectric material.
 16. The method of claim 2, further comprising doping said GST alloy with at least one of silicon and nitrogen.
 17. The method of claim 2, wherein the GST alloy is formed using a hydrogen or ammonia co-reactant.
 18. The method of claim 2, wherein the GST alloy is formed by chemical vapor deposition.
 19. The method of claim 2, wherein the GST alloy is formed by atomic layer deposition.
 20. The method of claim 1, further comprising precursor liquid delivery.
 21. The method of claim 20, wherein said liquid delivery comprises a liquid delivery medium including at least one solvent species selected from the group consisting of alkane solvents, ethers, aryl solvents, amines, imines, guanidines, amidines and hydrazines.
 22. The method of claim 2, further comprising doping the GST alloy to reduce its reset current. 